1. Field of the Invention
The invention relates to an ink jet recording head which is formed by laminating plate members and which is designed to form a dot on a recording sheet by splashing an ink droplet upon reception of an input of print data.
2. Prior Art
On-demand ink jet recording heads that are designed to output characters and graphics by jetting ink droplets from a plurality of nozzles in accordance with input information are rapidly gaining in popularity because of their high print quality and low noise compared with wire-dot type recording heads and because of their low running cost compared with page printers.
Among these ink jet recording heads, a so-called face-ejected ink jet head, which is designed to jet ink droplets in a direction perpendicular to the surface of a plate by arranging a plurality of nozzles on the plate, has features that a high degree of freedom is given to nozzle arrangement and that the head can be manufactured relatively simply because of a laminated structure.
FIG. 13 shows an exemplary ink jet recording head having the aforementioned laminated structure. A channel plate 94 defining slender pressure producing chambers 96 on a flat surface has one surface thereof sealed by a vibration plate 95 having piezoelectric vibration elements 97 formed so as to correspond to pressure producing chamber 96, and the other surface thereof sealed by a regulating plate 93 having regulating orifices 98.
A manifold plate 92 laminated on the surface of the regulating plate 93 has through holes that define reservoir chambers 99 for supplying ink to the respective pressure producing chambers 96 via the regulating orifices 98. Flow paths 100, 101, 102 which supply the ink from an ink tank and which runs through the vibration plate 95, the channel plate 94, and the regulating plate 93 are formed for the reservoir chambers 99.
Nozzles 90 plates 103 are formed in a nozzle plate 90 that is fixed to a side opposite to the vibration plate 95. Communicating holes 104, 105, 106 for connecting the nozzles 90 to the respective pressure producing chambers are formed so as to extend through the regulating plate 93, the manifold plate 92 and an additional plate 91 between the manifold plate 92 and the nozzle plate 103.
This laminated ink jet recording head is characterized in that the respective pressure producing chambers are typically arranged in two arrays so as to confront each other at an interval of from 0.04 to 0.06 inches within an array and are alternately connected to the nozzles pitched at an interval of from 0.02 to 0.03 inches within the single array.
By the way, to improve the recording quality of such ink jet recording head, it is necessary to increase the density of pixels to be recorded by downsizing an ink droplet to be jetted. Further, to ensure proper recording speed with the pixel density satisfied, it is necessary to increase the number of nozzles that jet ink droplets. Color printing, in particular, that forms a single pixel by three to four colors necessarily requires a great number of nozzles as well as a complicated flow path structure that can introduce the ink to such a great number of nozzles.
Particularly, to improve recording quality by increasing the density of pixels to be recorded, it is necessary to increase the nozzle arrangement density, which complicates the flow path structure between an ink containing section and the individual nozzles. This holds true not only for the plane dimensions and arrangement but for the thickness as well. To machine a smaller through hole in a plate in terms of the plane dimensions, it is necessary to reduce the thickness to a degree equal to the diameter of the hole.
To overcome these problems, a method of mounting a plurality of recording heads by staggering the nozzles is available. However, this method calls for an extremely high assembling accuracy in order to maintain the relative positioning accuracy among the respective recording heads.
The invention has been made in consideration of the aforementioned problems. Accordingly, an object of the invention is to provide a novel laminated ink jot recording head that can form nozzles at high accuracy by comparatively easy positioning operation.
Another object of the invention is to provide a novel laminated ink jet recording head that can be prepared inexpensively by utilizing the properties of two units, one being made of a metal material and the other being made of a ceramic material.
To achieve the above objects, the invention is applied to a laminated ink jet recording head that has a flow path unit being formed by laminating a nozzle plate, a reservoir chamber forming board, and an ink supply inlet forming board, the nozzle plate having nozzles divided into a plurality of groups, the reservoir chamber forming board having a plurality of reservoir chambers belonging to the respective groups of nozzles and having communicating holes respectively communicating with the nozzles, and the ink supply inlet forming board being fixed to a surface of the reservoir chamber forming-board and having communicating holes for communicating with pressure producing chambers and nozzles. In such laminated ink jet recording head, a plurality of actuator units are fixed to the flow path unit so as to correspond to the groups of nozzles, each actuator unit including a pressure producing producing chamber forming board, a vibration plate, and piezoelectric vibration elements, the pressure producing chamber forming board having a plurality of pressure producing chambers defined by side walls, the vibration plate being fixed to a surface of the pressure producing chamber forming board, and the piezoelectric vibration elements being formed on a surface of the vibration plate so as to correspond to the pressure producing chambers.
The flow path unit serving also as the actuator fixing board is made of metal that is relatively easy to ensure accuracy by press working or the like, and the actuator unit is made of ceramic that can be secured by sintering, so that accuracy in forming the nozzles of the flow path unit can be fully utilized.